Narrated Ibn Abi Na'm:I was present when a man asked Ibn `Umar about the blood of mosquitoes. Ibn `Umar said, "From where are you?" The man replied. "From Iraq." Ibn `Umar said, "Look at that! he is asking me about the blood of Mosquitoes while they (the Iraqis ) have killed the (grand) son of the Prophet. I have heard the Prophet (ﷺ) saying, "They (Hasan and Husain) are my two sweet-smelling flowers in this world."
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا مَهْدِيٌّ، حَدَّثَنَا ابْنُ أَبِي يَعْقُوبَ، عَنِ ابْنِ أَبِي نُعْمٍ، قَالَ كُنْتُ شَاهِدًا لاِبْنِ عُمَرَ وَسَأَلَهُ رَجُلٌ عَنْ دَمِ الْبَعُوضِ. فَقَالَ مِمَّنْ أَنْتَ فَقَالَ مِنْ أَهْلِ الْعِرَاقِ. قَالَ انْظُرُوا إِلَى هَذَا، يَسْأَلُنِي عَنْ دَمِ الْبَعُوضِ وَقَدْ قَتَلُوا ابْنَ النَّبِيِّ صلى الله عليه وسلم وَسَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ " هُمَا رَيْحَانَتَاىَ مِنَ الدُّنْيَا ".
Bukhari
Good Manners and Form (Al-Adab) • Hadith 25